Socket and a system for optoelectronic interconnection and a method of fabricating such socket and system

ABSTRACT

It is an object of the present invention to disclose a socket that is easy in use for optoelectrical interconnection. The socket of the invention can be handled as a compact device that allows the interconnection between electrical signals and external apparatus for transmitting the optical signals, preferably via a high density of optical channels.  
     The socket of the invention has features and markers for attachment and alignment of optical transfer media such as optical fibers, optical fiber bundles and optical imaging fiber bundles. The alignment features and markers allow to align the optical transfer media to the connection for electrical signals. The markers can be integrated in or can be provided on a fiber optic face plate substrate forming part of the socket.

FIELD OF THE INVENTION

[0001] The present invention relates to the field of semiconductordevice structures, and more in particular to optoelectrical oroptoelectronic devices. More precisely the present invention is relatedto a socket, and to a system for optoelectronic interconnection. Thepresent invention is also related to a method of fabricating suchsockets and such systems.

BACKGROUND OF THE INVENTION

[0002] The increased integration of transistors on single chips madepossible by the submicron CMOS technology raises the problem of speedand performance limitation of electronic systems through theinterconnect structures between chips or with other structures. Apossible solution to this problem of CMOS interconnect bottlenecks couldbe the use of optical links or interconnects between chips. In a numberof applications, especially to achieve high density interconnects,optical interconnects are advantageous over electrical interconnects.For instance, optical interconnects can reach a higher interconnectdensity and lower power consumption than electrical interconnects.

[0003] In order to achieve high density optical interconnects, it isnecessary to realize high density arrays of light sources and lightdetectors, and furthermore to use an optical path or channel betweensources and detectors which sustains a high density of optical channels.The light sources used to send the optical signals through the opticalinterconnect channels receive their input and possibly at least part oftheir power from electrical signals. These electrical signals canoriginate from an integrated circuit, or from a board. Furthermore, atthe other end of the optical interconnect channel are detectors, whichalso require electrical power to operate, and which convert the receivedoptical signals into electrical signals. Hence, it is clear that highdensity optical interconnects require a high density of electrical oroptical devices to possibly deliver at least part of the requiredelectrical power to run the optical interconnect, as well as to send andretrieve the signals.

[0004] Obviously, the foregoing analysis can be applied as well tointerconnect systems that make use of another form of electromagneticradiation than light.

[0005] In many optical applications, it is required to have atransparent substrate for an optoelectronic device such as alight-emitting device, a photodetector, a modulator or a CCD sensor. Anapplication example is when an optoelectronic device is contacted fromthe front side by flip-chip mounting, while the light has to betransported through the substrate. Many substrates are poorly or nottransparent for the light emitted or detected in the activesemiconductor layers grown on them. For example, Gallium-Arsenide (GaAs)or Aluminium-Gallium-Arsenide (AlGaAs) or InGaP or InAlGaP active layersemit and detect light with a peak wavelength that is strongly absorbedby the GaAs substrate on which they are typically grown. Hence,light-emission or light-detection through the original substrate is notpossible. A possible solution to this problem is to remove the originalsubstrate in a process such as described in U.S. Pat. No. 5,578,162.Another possible solution is to replace the original substrate by atransparent substrate, such as a glass plate.

[0006] U.S. Pat. No. 5,093,879 discloses an optoelectrical connector foraccommodating high density applications. This patent specificationhowever does not disclose and does not enable to fabricate integrationneither alignment of a connection for the electrical signals to thedevices for emitting and/or detecting electromagnetic radiation, whereinthe functioning of said devices is being controlled by said electricalsignals.

[0007] U.S. Pat. No. 5,625,811 discloses an optically interconnectedmultichip module. The patent shows a dense integration of thin layers ofsemiconductor material with devices (chips) integrated therein and whichare bonded to a fiber optic face plate. These chips are integrated in amultichip module and the fiber optic face plate is providing the opticalintraconnection or optical transmission medium between the chips. Theoptical intraconnection (waveguide) is not flexible and does not allowfor communication between chips which are in the same plane or in aremote location. This patent does not address the problem of a connectorto an external apparatus or external devices that is versatile in useand easy to use.

[0008] The use of fiber optic face plates in combination withoptoelectrical devices has further been proposed, e.g. in U.S. Pat. No.5,074,683, and in U.S. Pat. No. 5,652,811, and in U.S. Pat. No.5,578,162.

[0009] U.S. Pat. No. 5,631,988 discloses an optical interconnect thatcouples multiple optical fibers to an array of optoelectrical devices.The connector comprises a holder, a plurality of optical fibers attachedto the holder, and guiding means. This connector is quite elaborate andnot compact in providing the optical path of the interconnectionsignals. Moreover, the direct contact of the optical fiber bundles tothe optoelectrical devices can degrade such devices, in particularbecause the optical connection is detachable.

[0010] U.S. Pat. No. 5,367,593 provides an optical/electrical connectorthat includes a molded base with alignment guides and with a well forintegrating an electronic circuit. Also this device is not compact andprovides an optical interconnection path only for a 1-dimensional array.The teaching of this patent does not disclose nor does it suggest anoptoelectrical interconnect in a dense and compact configuration whichis flexible in use for a multitude of configurations such as2-dimensional arrays of light-emitting devices on an electronic circuit.

SUMMARY OF THE INVENTION

[0011] It is an object of the present invention to disclose a socketthat is easy in use for optical or optoelectronic or optoelectricalinterconnection. The socket of the invention provides an interconnectiondevice that has a dense, compact configuration. In an embodiment of theinvention, the socket of the invention can be handled as a stand-alonepackage that allows the interconnection between electrical signals andan external apparatus for transmitting the optical signals, preferablyvia a high density of optical channels. The socket of the inventionallows for a flexible communication between devices being controlled byelectrical signals such as integrated circuits. With the socket of theinvention a communication between chips in an in-plane configuration orin any other configuration or dimension is feasible. A communicationbetween chips in an in-plane configuration (a 2-dimensional array ofchips) or in any other configuration or dimension (for instance a1-dimensional or 3-dimensional array) is feasible.

[0012] It is another object of the present invention to provide a socketfor optoelectrical interconnection with a transparent substrate forhigh-density optical input/output applications in which the electricalinput/outputs are connected to the optical input/outputs. But theelectrical input/outputs are at another side of the socket, preferablyopposite, to the optical input/outputs.

[0013] It is a further object of the invention to disclose a socket withfeatures and markers for attachment and alignment of optical transfermedia such as optical fibers, optical fiber bundles and optical imagingfiber bundles. The alignment features and markers allow to align theoptical transfer media to the connection for electrical signals. Themarkers can be integrated in or can be provided on a fiber optic faceplate substrate forming part of the socket. The alignment features andmarkers in an embodiment of the invention can comprise magnetic meansfor alignment and/or attachment. The optical fibers, fiber bundles orimaging fiber bundles can then further be aligned and attached todetectors integrated in a silicon integrated circuit.

[0014] Thus, here is provided a socket for optoelectricalinterconnection, comprising a connection for electrical signals; anarray of devices emitting and/or detecting electromagnetic radiation,the functioning of said devices being controlled by said electricalsignals; and a connection to an external apparatus, the connectionincluding a transmitter or a channel for said radiation. Said connectionfor electrical signals can be connected with at least a part of saiddevices of said array. Said connection for electrical signals can bealigned through at least one marker in or on said connection to saidexternal apparatus with at least a part of said devices of said array.The marker can be aligned with at least part of said devices of saidarray. Said external apparatus can include a channel or a high densityof channels for said electromagnetic radiation. The external apparatuscan also include a detector and/or devices for emitting electromagneticradiation. Said connection for electronic signals can be at a first sideof said socket and said connection to said external apparatus can be ata second side of said socket.

[0015] The socket of the invention can be configured as aninterconnection device for optoelectrical interconnection, comprising aconnection for electrical signals; an array of devices emitting and/ordetecting electromagnetic radiation, the functioning of at least a partof said devices being controlled by said electrical signals; andconnection to an external apparatus including a transmitter for saidradiation, said connection to said external apparatus comprising asubstrate with a plurality of light channels for said radiation. Theconnection can be such that essentially each device of said array isaligned with at least a subset of said light channels. In an embodimentof the invention, said substrate can be a fiber optic face plate.According to this embodiment of the invention, the different parts ofthe interconnection device or socket are brought together adjacent oneto another in a dense, compact configuration. The different parts canhowever be spatially separated. According to a preferred embodiment,such dense configuration can be achieved with having the different partsof the socket integrated on a substrate such as a PCB-board with amounting technique, such as a flip-chip technique for mounting theparts, providing the alignment of the different parts one to another.

[0016] In an advantageous embodiment of the invention, the fiber opticface plate can include microlenses. The microlenses can be madeaccording to the teaching of U.S. Pat. No. 5,871,888 or of any patent orreference cited within or with respect to this patent, U.S. Pat. No.5,871,888 or any of the prior art teachings being incorporated herein byreference.

[0017] The socket of the invention can also be configured as anintegrated socket providing the socket of the invention in a compact,single interconnection device with each of the different parts of thesocket is abutting at least one of the other parts of the socket.

[0018] The socket of the invention can also have at least one marker insaid connection to said external apparatus, said marker being alignedwith at least part of said devices of said array.

[0019] In a preferred embodiment of the invention, in the socketessentially each of said devices for emitting and/or detectingelectromagnetic radiation of said array is being confined through formand functioning and essentially each of said devices for emitting and/ordetecting electromagnetic radiation of said array is being aligned withat least a part of said connection for electronic signals. With the termconfined through form and functioning it is meant that withoutadditional means or without additional structural features such asextended, large isolation features in the array of devices, each of saiddevices can be addressed individually via the connection for electricalsignals. Such confinement through form and functioning can be done e.g.when said devices are being integrated in a single thin filmsemiconductor. The term confined through form and functioning is alsoused more generally in this specification. For instance, in anembodiment of the invention, said connection for electronic signals caninclude an electrically conducting glue providing separate conductionpaths. These paths can be confined through form and functioning whichmeans that without additional means the glue is providing a separateconduction path to substantially each of the devices. Also detectordevices can be used that are confined through form and functioning.

[0020] In an embodiment of the invention, one can also use devices thatcan both emit and detect electromagnetic radiation. Examples of suchdevices are optical thyristors or p-n diodes.

[0021] In a preferred embodiment of the present invention, said socketincludes a thin-film semiconductor layer attached to a transparent fiberoptic face plate substrate, such that optoelectrical devices processedin the thin film semiconductor layer are electrically contacted from theside opposite to the side of the faceplate attachment. Markers andmarker features for alignment are made in or on the fiber optic faceplate. In an aspect of the invention, two sockets are abutted oneagainst the other and information is transmitted between the lightemitters/detectors of the respective sockets. An example of such use isthe information transmission to and from a board with electronic devicesto a rack including a multiple of such boards.

[0022] Still a further object of the invention is to disclose a systemfor transmitting information comprising at least one channel forelectromagnetic radiation; a socket for optoelectronic interconnection,and said channel comprising a channel marker, said channel marker beingaligned with a socket marker. The socket includes a connection forelectronic signals; an array of devices emitting and/or detectingelectromagnetic radiation, the functioning of said devices beingcontrolled by said electronic signals, said connection being connectedand aligned with at least a part of said devices of said array; aconnection for said channel for said radiation; and at least one socketmarker in said connection for said channel, said marker being alignedwith at least part of said devices of said array. The system can furthercomprise an array of devices emitting and/or detecting electromagneticradiation, said array of devices being connected to said channel, thedetectors of said array being adapted for receiving said radiation andconverting said radiation into electronic signals. Said detectors canfurther comprise detector markers such that said channel is aligned withsaid detector markers and such that specific parts of said array ofradiation emitting devices are aligned with specific parts of saiddetector.

[0023] Yet another object of the invention is to disclose a method offabricating an optoelectrical structure wherein the optical devicesforming part of the structure are controlled by electrical connectionsthat can be aligned with an external channel for transmitting theoptical information. The method of fabricating the optoelectricalstructure provides a way of aligning the different parts of theoptoelectrical structure one with respect to the other.

[0024] In an embodiment of this object of the invention, a method oflarge-scale and wafer-scale fabrication of arrays of optoelectronicdevices with above-mentioned transparent fiber optic face platesubstrate is disclosed. A preferred embodiment of the invention revealswafer scale fabrication of the optoelectronic devices on a fiber opticface plate including integrated socket features.

[0025] Yet any combination can be made of any of the embodiments of thedevices or methods of the invention, disclosed in the present patentapplication.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Exemplary embodiments of the invention and of the use of theinvention are shown in the drawings. The drawings are schematicrepresentations of the invention and therefore the dimensions and therelative dimensions do not correspond to actual reductions to practiceof the invention.

[0027]FIG. 1 depicts a socket according to an embodiment of the presentinvention. The socket comprises a thin semiconductor film withoptoelectrical devices therein and a fiber optic face plate for opticalconnection. Said socket is attached to a carrier for electricalconnection, at a side opposite to said fiber optic face plate.

[0028]FIG. 2a depicts a socket according to a preferred embodiment ofthe present invention. The socket comprises a thin semiconductor filmwith electronic devices therein and a fiber optic face plate containingmarkers. Said socket is attached to a carrier at a side opposite to saidfiber optic face plate.

[0029]FIG. 2b depicts a socket according to another preferred embodimentof the present invention. The socket comprises a thin semiconductor filmwith electronic devices therein and a fiber optic face plate. A piecefor attachment and alignment containing markers is glued on the faceplate. Said socket is attached to a carrier at a side opposite to saidfiber optic face plate.

[0030]FIG. 2c depicts a socket according to an alternate embodiment ofthe present invention. The socket comprises a thin semiconductor filmwith electronic devices therein and a fiber optic face plate. A piecefor attachment and alignment containing markers is connected to the faceplate. Said socket is attached to a carrier at a side opposite to saidfiber optic face plate.

[0031]FIG. 2d shows in detail the thin semiconductor film with theoptoelectronic devices therein being confined through form andfunctioning and with the electrodes contacting the devices.

[0032]FIGS. 3a , 3 b depict the use of a socket of FIG. 2a and FIG. 2brespectively wherein a plug is attached as an external apparatus to thesocket. Said plug can hold a light-guiding device such as an imagingfiber bundle or a bundle of fibers.

[0033]FIG. 4 illustrates a system for transmitting electronicinformation over an optical link. The system is configured as an opticalinterconnect using two socket structures.

[0034]FIGS. 5a and 5 b illustrate the use of the socket of FIG. 2. as anoptical connection window for optical channels in an hermetically sealedpackaged chip.

[0035]FIG. 6 shows a wafer-scale fabrication process to manufacture thesockets according to the present invention.

[0036]FIG. 7 shows another wafer-scale fabrication process tomanufacture the sockets according to the present invention.

[0037]FIG. 8 shows an alternative wafer-scale fabrication processincluding a step of epitaxial lift-off.

[0038]FIG. 9 illustrates an embodiment of the processing of a fiberoptic face plate for use in the fabrication of the present invention.

DETAILED DESCRIPTION OF SEVERAL EMBODIMENTS OF THE PRESENT INVENTION

[0039] The invention is described in the sequel through a detaileddescription of several embodiments of the invention. It is obvious thatother embodiments of the invention can be configured according to theknowledge of persons skilled in the art without departing form the truesprit of the invention, the invention being limited only by the terms ofthe appended claims.

[0040]FIG. 1 depicts a socket 1 according to one embodiment of thepresent invention. One surface 111 of a thin-film semiconductor 11 isattached to a fiber optic face plate 13. Optoelectrical oroptoelectronic devices 121, 122, etc., generally referred to as 12, arefabricated in the thin-film semiconductor 11. Means for electricallyconductive bonding 14 are provided at the other surface 112 of thethin-film semiconductor, and perform the double function of mechanicallyattaching the thin-film semiconductor to a carrier 15, and providingelectrical connection between said carrier and said optoelectronicdevices.

[0041] The carrier 15 can be an integrated circuit. It can, however,also be a multichip module, a board such as a printed circuit board, apart of a connector, or, in general, any carrier that provideselectrical signals and/or electrical power to the optoelectronic devices12.

[0042] Examples of possible means for electrically conductive bonding 14are metal bumps, solder balls, conductive epoxy, conductive polymers andequivalents. Said means include a combination of a means for electricalfeed-through, such as metal bumps, with a means for mechanicalattachment, such as underfill, glue, resist, epoxy, or equivalentproducts.

[0043] Based on the knowledge of person skilled in the art, a glue canbe chosen that is an electrically conducting glue which allows forseparate conduction paths through form and functioning.

[0044] The fiber optic face plate 13 transmits optical inputs andoutputs of the optoelectronic devices 12. The attachment 16 of thin-filmsemiconductor 11 to fiber optic face plate 13 has to be transparent forthe light of the optoelectronic devices. Attachment 16 is preferablydone by means of an epoxy, including EPO-TEK 353ND of Epoxy TechnologyInc, or a polyimide, including PIQ-13 of Hitachi chemical, thatwithstand high temperatures (several hundreds degrees Celsius). However,the invention also covers the use of other means of attachments, such assoldering glass or direct bonding of the thin-film semiconductor 11 tothe fiber optic face plate 13.

[0045] According to a preferred embodiment of the invention, depicted inthe FIG. 2a, fiber optic face plate 13 has markers 211 including groovesand holes. The markers 2111, 2112 can also be fabricated upon the fiberoptic face plate instead of in the fiber optic face plate as shown onthe drawings 2 b and 2 c. The FIGS. 2b and 2 c show a piece 23 forattachment and alignment containing markers. The piece 23 can beattached, for instance with a glue 24, on the face plate 13 while inalignment to the structures 112 that are already processed. Shown in theFIGS. 2b and 2 c are the piece (23) for attachment and alignmentcontaining at least one marker (2121, 2131) for alignment and at leastone cavity (2122, 2132) for attachment including at least one structure(2123, 2133) for clamping the feature of the external apparatus meantfor fixing the external apparatus.

[0046] Thus the markers generally labelled as 21 include markers 2111,2121, 2131 for aligning and features 2112, 2122, 2132 for attaching anexternal apparatus through a plug. The markers can also be receptaclesfor pins. With markers 21 in or on fiber optic face plate 13, thestructure can be used as a socket. The socket can comprise a thinsemiconductor film with optoelectronic devices therein and is attachedto a carrier at one side and to a fiber optic face plate at anotherside. An advantage of providing markers 21 preformed in or on face plate13 is that alignment of the optoelectronic devices 12 to said featurescan be obtained during the fabrication of the socket. This will befurther clarified below.

[0047] In the preferred embodiments of the invention (FIGS. 2a, 2 b, 2c), the optoelectronic devices for emitting radiation are confinedthrough form and functioning. Each of said devices is aligned with atleast a part of said connection for electrical signals. The confinementthrough form and functioning is shown in detail in FIG. 2d where theconfinement is realized through mesa etch confinement and currentconfinement by a limited lateral oxidation 28. The technique of mesaetching is known to the person skilled in the art. Ways of realizing theconfinement can be current confinement, proton confinement or oxideconfinement. In essence, an extended space charge layer is to be definedin order to isolate the devices one from another and to realize in thisway the confinement through form and functioning of the device. Each ofthe devices can be addressed individually through the metal gridstructure 27 on one side of the thin semiconductor layer and the solderballs 14 on the other side of the semiconductor layer. In general, everyoptoelectronic device 12 has two electrodes. Arrays of optoelectronicdevices can be operated with one electrode common to all devices of thearray, or with separate electrodes for each device of the array.

[0048]FIGS. 3a and 3 b depict the use of a plug 311, 312 connected to asocket. Plugs 311, 312 have means for alignment 3111, 3121 and means forattachment 3112, 3122. In an embodiment of the invention shown in FIG.3a, the plug 311 can have means for alignment 3111 and means forattachment 3112 that mate to markers 211 and 212 of a socket accordingto the invention, respectively. Plug 311 can be the termination 311 of alight-guiding device 33, that could, for example, be an imaging fiberbundle or a bundle of optical fibers. The plug-terminated light-guidewill henceforth be referred to as structure 34. By plugging structure 34into the socket, the optical inputs and outputs of the optoelectronicdevices 12 can be transported to a remote location. Moreover, becauseoptoelectronic devices 12 can be aligned to the markers 2111 of thesocket during fabrication, and because markers 2111 mate to markers 3111of plug 311, plug 311 automatically aligns to the optoelectronic devices12 when it is snapped into the socket.

[0049]FIG. 3b shows the alignment and the attachment of a plug 312 tothe socket of FIG. 2b. More particularly is shown a fiber bundle 33terminated by a plug 312. Plug 312 includes a part that slides into thecavity 2122 and, when pushed, the structure 35 will snap behind thestructure 2123 such that the plug 312 cannot slide out of the structure23 any more. To release it, the spring 36 has to be pressed andsimultaneously the fiber 33 has to be pulled out. The alignment isautomatically arranged by the marker 3121 that is guided in thealignment cavity 2121. A minimum distance of the fiber end to the faceplate 13 can be set by the stud 37.

[0050] Further, FIG. 4 illustrates the use and advantages of thisalignment According to this aspect of the invention, the plug can beused as holder for an array of optoelectronic devices that match withanother array of optoelectronic devices. For example, in case theoptoelectronic devices of one array are light-emitting devices, the plugcan contain an array of detectors that are essentially aligned to theemitters when the plug is snapped into the socket.

[0051] An application in a system for transmitting electricalinformation and for providing an optical interconnect between two chipsis disclosed. The system is a basic building structure for paralleloptical interconnects between chips. Imaging fiber bundles, well knowfrom medical imaging, and used among others in endoscopes, transport animage from one place to another with a one to one correlation betweenlight input and light output image.

[0052] In detail, in FIG. 4 are shown a first socket structurecontaining emitters 421 and detectors 431, aligned to markers 441 of afirst fiber optic face plate and a second socket structure, containingemitters 422 and detectors 432, aligned to markers 442 of a second fiberoptic face plate. The arrays of light emitting devices are spaced verydensely, in arrays on a pitch of 100 micron or even less. A light-guide43 is also shown having both its ends terminated with a plug. A firstplug fits into the first socket and aligns to the markers of said firstsocket. The second plug fits into the second socket and aligns to themarkers of said second socket. Both ends of the plug-terminatedlight-guide 43 are to be snapped into their respective sockets. Alllight detectors 432 face corresponding emitters 421, and all lightdetectors 431 face corresponding emitters 422, by simple mechanicalalignment. This is due to the cascade of alignments of the devices 421and 431 to markers 441, markers 441 to plug 451, plug 451 to light-guide43, light-guide 43 to plug 452, plug 452 to markers 442, and of markers442 to devices 422 and 432.

[0053] An example of the use of the socket of the invention is shown inFIG. 5. In this example, the carrier 15 is an integrated circuit die 51.Integrated circuit die 51 is attached to a package base 53. Electricalwires 52 connect electrical input and output pads of the integratedcircuit die to pins 54 of the package. Now, according to the presentinvention, the socket of FIG. 2 can be used for providing optical inputsand outputs to the integrated circuit. As shown in FIG. 5, more than onesocket can be provided on the same integrated circuit die 51. Theoptoelectronic devices 12 integrated on sockets can includelight-emitters, such as Vertical-cavity Surface Emitting Lasers (VCSELs)or Light-Emitting Diodes (LEDs). They also can include detectors such asp-i-n diodes. Alternatively, the detectors can be integrated in theintegrated circuit die 51 rather than in the thin-film semiconductor 11.

[0054] As shown in FIG. 5, an integrated circuit die 51 mounted on andbonded to package base 53 can be further capped, for example withplastic moulding 55, leaving sockets accessible for attachment oflight-guides. In this way, the electrically and optically interconnectedintegrated circuit 51 is completely protected from the environment,while still accepting optical inputs and outputs. Therefore, thedescribed method results in the fabrication of a practical electricallyand optically interconnected integrated circuit 51. Electrically andoptically interconnected integrated circuit 51 can safely be shipped,mounted onto a board, and undergo other handling operations. It is morerobust and practical to use and to mount than a pig-tailed chip—this isa chip which has light-guides attached to it—and than apartially-uncovered chip—in which a part of the integrated circuit whichis intended to offer optical accessibility is naked and unprotected fromthe environment.

[0055] As mentioned previously, the optoelectronic devices 12 can bealigned to circuitry of the integrated circuit 51 during the applicationof the electrically conductive bonding 14. For example, if theelectrically conductive bonding consists of solder balls, optoelectronicdevices 12 are aligned during the flip-chip bonding process.Furthermore, as stated above, the optoelectronic devices can be alignedto the markers 21 of the fiber optic face plate 13 during thefabrication of the socket of the invention. Hence, when a plugexemplified by 311, 312 is attached to a socket of the invention, it isautomatically aligned to both the optoelectronic devices 12 of saidsocket and to the underlying circuitry in integrated circuit die 51.Therefore, a connection such as depicted in FIG. 4 can be organizedbetween several sockets of the invention on an electrically andoptically interconnected integrated circuit 51, creating intra-chipoptical interconnects. Also, such connection can be established betweensockets of the invention on different electrically and opticallyinterconnected integrated circuits 51, creating inter-chip opticalinterconnects between said chips.

[0056] By using a socket structure of the invention on an integratedcircuit die 51 to create electrically and optically interconnectedintegrated circuit 51, the total area of optoelectronic semiconductormaterial consumed is small as compared to the area of the siliconintegrated circuit. This is favorable, because the price ofoptoelectronic semiconductor material per unit area is normally muchlarger than the price of silicon integrated circuits per unit area.Therefore, the proposed method for fabricating an electrically andoptically interconnected integrated circuit 51 is economically morecompetitive than methods including bonding of an optoelectronicsemiconductor wafer to a silicon wafer.

[0057] According to another aspect of the invention, the use of a socketstructure including a fiber optic face plate for providing opticalconnection to an integrated circuit is extended to the case where theoptoelectronic devices are integrated in the integrated circuit ratherthan on a thin-film semiconductor. A fiber optic face plate withfeatures is aligned to circuitry including optoelectronic devices in acarrier, which, in a preferred embodiment, is an integrated circuit die.The attachment means of the fiber optic face plate to carrier istransparent, and includes the use epoxy, cyanoacrilate glue andpolyimide. In a preferred embodiment, said optoelectronic devicesinclude detectors integrated in silicon circuitry.

[0058] A preferred method for fabricating structures according to thepresent invention is disclosed in FIG. 6A to FIG. 6F. Shown in FIG. 6Aare epitaxial layers (surface layers) 611, 612 grown on a substrate 62,which can be a semiconductor, typically selected from group IV, groupIII-V or group II-VI, or a dielectric material, such as sapphire. Theepitaxial layers include layers 612 for selectively stopping a chemicaletch and layers 611, that include a junction between two semiconductormaterials of opposite doping type. Henceforth, the combination ofepitaxial layers 611, 612 with substrate 62 is called the semiconductorstructure 63. After the growth, partial processing of semiconductordevices can be started, as shown in FIG. 6B. This partial processing ishenceforth called “rear side processing” 641, because it will ultimatelybe located at the rear side of the optoelectronic devices. Rear sideprocessing 641 can typically be the deposition of a metal grid 6411 ontop of the epitaxial layers 611, 612. It can also consist of aroughening 6412 of the surface of the epitaxial layers, using a processsuch as lithography. Shown in FIG. 6C, the semiconductor structure 63 isthen flipped over, and epitaxial layers 611 are attached to a fiberoptic face plate 13. Said face plate can have preformed markers 211.Preferred means 16 for attachment of the epitaxial layers 611 to thefiber optic face plate 13 is a transparent, low-shrinkage, temperatureresistant epoxy or polyimide. If rear side processing 641 is used toprocess structures in the epitaxial layers 611, and if the fiber opticface plate 13 contains markers 211, then alignment of said processedstructures to said markers 211 is necessary during the attachment of theepitaxial layers 61 to the fiber optic face plate 13. The next step,illustrated in FIG. 6D, is the removal of substrate 62. Mechanicalgrinding and polishing, as well as chemical etching can be used to thisend. This removal process stops in one of the epitaxial layers 612, suchthat at least layers 611 remain intact. An example of an adequatesubstrate removal technique is given in U.S. Pat. No. 5,578,162. Afterthis substrate removal, processing of optoelectronic devices 12 iscontinued, as shown in FIG. 6E. It is called “front side” processing642. If fiber optic face plate 13 contains markers 211, then the frontside processing requires alignment to the markers 211. This isstraightforward to achieve with reasonable precision, because markers211 are imaged by the fiber optic face plate to the interface betweenfiber optic face plate 13 and epitaxial layers 611, and are visiblethere through the thin-film semiconductor. After front side processingof optoelectronic devices, means for electrically conductive bonding 14are provided to contact the optoelectronic devices 12, as shown in FIG.6F. A preferred means for electrically conductive bonding are solderballs. The structure generally depicted in FIG. 6F will further bereferred to as structure 68.

[0059] The fabrication method disclosed so far can be applied to waferlevel. This is advantageous for mass production and low-costmanufacturing. The above-disclosed fabrication technique allowsoptoelectronic devices 12 to be aligned both to the backside processing641 and to markers 211 preformed in the fiber optic face plate 13 overthe complete wafer. This alignment can be achieved using conventionalalignment tools and techniques. The alignment of the different parts ofthe socket of the invention in fact is provided by way of thefabrication method.

[0060] Fabrication of a structure according to the invention isterminated by separating an individual die 69 from structure 68, asshown in FIG. 6G, and bonding it to a carrier 15. In case the means forelectrically conductive bonding 14 are solder balls, the bondingtechnique is flip-chip joining, eventually followed by filling of thespace between carrier 15 and epitaxial layers 611 using, for example, anunderfill, glue, epoxy, resist, or equivalent.

[0061] In an alternative fabrication method of the structure accordingto the present invention, the means for electrically conductive bonding14 is applied to a carrier 15 rather than to structure 68. The processsequence as described above can also be applied for a face plate whichdoes not contain markers. This is shown in FIGS. 7A-7F. FIG. 7G shows apiece 72 including markers can be attached to the face plate using forinstance glue 24. This can occur on wafer level before cleavage of theindividual sockets 78. In an alternative process sequence, the markerscan be attached after cleavage of the sockets 78. For both alternativesthe markers can be aligned to the optoelectronic devices.

[0062] Another method for fabricating the structure according to theinvention, is described in FIG. 8. The thin-film semiconductorcontaining epitaxial layers that include a p-n junction are separatedfrom the original substrate by epitaxial lift-off. Devices can beprocessed before or after transfer of said thin-film semiconductor tothe fiber optic face plate. In the preferred embodiment, the processingis done after film transfer. FIG. 8A depicts transferred epitaxial films82, containing a p-n junction, attached to a fiber optic face plate 13.As shown in FIG. 8A, several epitaxial films 821, 822, . . . can bejuxtaposed. This is useful, because it is notoriously difficult tolift-off an epitaxial film having the size of a wafer, and therefore itis desired to lift-off smaller pieces. The processing of theoptoelectronic devices can proceed analogously as in the case explainedin FIG. 6E to FIG. 6F. The structure obtained after processing is shownin FIG. 8B, and is referred to as structure 81. An alignment ofoptoelectronic devices 12 to markers 211 in the fiber optic face plate13 is obtained during device processing, analogously as in thepreviously-described method. The application of the means forelectrically conductive bonding is also analogous the said applicationin the above-described processing method.

[0063] In FIG. 9 is shown an embodiment of the processing of the fiberoptic face plate to create the markers for use in the fabricationmethods of FIG. 6. FIG. 9A shows the top side of the face plate,perpendicular to the fibers in the plate. FIG. 9B shows thecross-section, with the fibers running vertically. The grooves 92 aresawn into the fiber optic face plate 91, for instance in a squarepattern. The bottom of the groves has a shape suited for controlledcleaving of the fiber optic face plate after completion of theprocessing, as shown in FIG. 6G. Grooves 92 extend from one side to theother of the fiber optic face plate. Laser machining or milling can beused to create a notch 94 at both sides of the groves 92. Together withthe groove 92, this notch will turn into the receptacle 2112 for theplug feature 3112 after cleavage of one chip, exemplified as 69, fromfiber optic face plate 91. Features 2111, that guide alignment pins 311of plug 311, can be made in the surface of the fiber optic face plate byprecision drilling or laser machining. Features 2111 can consist of acircular hole 95 with a tapered end 96 for easy insertion of thealignment pins 3111.

1. An interconnection device for optoelectrical interconnection,comprising: a connection for electrical signals; an array of devicesemitting and/or detecting electromagnetic radiation, the functioning ofat least a part of said devices being controlled by said electricalsignals; and a connection to an external apparatus, the connectionincluding a transmitter for said radiation, said transmitter comprisinga substrate with a plurality of light channels for said radiation
 2. Theinterconnection device as recited in claim 1 wherein essentially eachdevice of said array is aligned with at least a subset of said lightchannels.
 3. The interconnection device as recited in claim 1 whereinsaid external apparatus is attached, preferably in a removable way, bymecahnical or electromagnetic means or by a combination thereof to saidconnection to said external apparatus.
 4. The interconnection device asrecited in claim 1 wherein said substrate is a fiber optic face plate.5. The interconnection device as recited in claim 1 having at least onemarker in said connection to said external apparatus, said marker beingaligned with at least part of said devices of said array.
 6. Theinterconnection device as recited in claim 1 wherein said connection forelectrical signals, said array of devices and said connection to saidexternal apparatus are integrated in an integrated socket, and whereineach of said connection for electrical signals, said array of devicesand said connection to said external apparatus are abutting at least toone other of said connection for electrical signals, said array ofdevices and said connection to said external apparatus.
 7. The socket asrecited in claim 6 wherein essentially each device of said array ofdevices can be addressed individually via said connection for electricalsignals.
 8. The socket as recited in claim 6 wherein said connection forelectrical signals is connected and aligned with at least a part of saiddevices of said array.
 9. The socket as recited in claim 6 wherein saidexternal apparatus comprises of at least one channel for saidelectromagnetic radiation.
 10. The socket as recited in claim 6 whereinsaid external apparatus includes at least one detector and/or devicesfor emitting electromagnetic radiation.
 11. The socket as recited inclaim 6 having at least one marker in said connection to said externalapparatus, said marker being aligned with at least part of said devicesof said array.
 12. The socket as recited in claim 6 wherein saidconnection for electrical signals is being directly connected with atleast a part of said devices of said array.
 13. The socket as recited inclaim 6 wherein said connection for electrical signals is at a firstside of said socket and said connection to said external apparatus is ata second side of said socket.
 14. The socket as recited in claim 6wherein essentially each of said devices emitting and/or detectingelectromagnetic radiation is being confined through form and functioningand wherein essentially each of said devices of said array is beingaligned with at least a part of said connection for electrical signals.15. The socket as recited in claim 6 wherein said marker is at least onegroove in said fiber optic face plate.
 16. The socket as recited inclaim 6 wherein said marker is deposited upon said fiber optic faceplate.
 17. The socket as recited in claim 6 further comprising aradiation transparent attachment for attaching said fiber optic faceplate to said array of devices.
 18. The socket as recited in claim 6wherein said array of devices is integrated in a single first substrate.19. The socket as recited in claim 6 wherein said connection forelectrical signals comprises a plurality of connection paths and whereineach of said paths is being connected to a specific subset of saiddevices of said array.
 20. The socket as recited in claim 6 wherein saidconnection for electrical signals comprises a plurality of connectionpaths and wherein each of said devices emitting and/or detectingelectromagnetic radiation is being connected to a specific subset ofsaid paths.
 21. A plurality of sockets as recited in claim 6, saidplurality of sockets being mounted on one common surface of a carrier.22. The plurality of sockets as recited in claim 21 being at leastpartly encapsulated.
 23. The socket as recited in claim 6 wherein saiddevices are light emitting devices being integrated in a single thinfilm semiconductor, essentially each of said devices of said array beingconfined through form and functioning.
 24. The socket as recited inclaim 23 wherein said connection for electrical signals includeselectrically conducting solder balls.
 25. The socket as recited in claim23 wherein said connection for electrical signals includes anelectrically conducting adhesive.
 26. The socket as recited in claim 25wherein said adhesive is a glue providing separate conduction paths. 27.The socket as recited in claim 25 wherein said adhesive is a glueproviding conduction paths that are separate through form andfunctioning.
 28. The socket as recited in claim 6 wherein said devicesare detectors being integrated in a semiconductor substrate, saidsubstrate comprising said connection for electrical signals.
 29. Thesocket as recited in claim 6 wherein said external apparatus isattached, preferably in a removable way, by mecahnical orelectromagnetic means or by a combination thereof to said connection tosaid external apparatus.
 30. A system for transmitting informationcomprising a channel for electromagnetic radiation and a socket foroptoelectrical interconnection, said socket including: a connection forelectrical signals; an array of devices emitting and/or detectingelectromagnetic radiation, the functioning of said devices beingcontrolled by said electrical signals, said connection for electricalsignals being connected and aligned with at least a part of said devicesof said array; a connection to said channel for said radiation and atleast one socket marker in or on said connection to said channel, saidmarker being aligned with at least part of said devices of said array,said connection to said channel comprising a substrate with a pluralityof light channels for said radiation and said channel comprising achannel marker, said channel marker being aligned with said socketmarker.
 31. The system as recited in claim 30 further comprising anarray of devices emitting and/or detecting electromagnetic radiation,said array of devices being connected to said channel, the detectors ofsaid array being adapted for receiving said radiation and convertingsaid radiation into electrical signals.
 32. The system as recited inclaim 30 wherein said detectors of said array comprise detector markerssuch that said channel is aligned with said detector markers and suchthat specific parts of the array of radiation emitting devices arealigned with specific parts of the array of detector devices.
 33. Amethod of fabricating an optoelectrical apparatus comprising the stepsof: providing an array of devices for emitting and/or detectingelectromagnetic radiation in a first substrate on a first side of saidsubstrate; attaching said first substrate to a second substrate, saidfirst side being on said second substrate and being transparent for saidradiation; providing markers in or on said second substrate therebyensuring that said markers are aligned with the devices of said array;providing electrical connections to said array of devices.
 34. Themethod as recited in claim 33 wherein while providing electricalconnections to said array of devices, it is ensured that essentiallyeach of said devices are addressed individually.
 35. The method asrecited in claim 33 further comprising the step of: growing at least onesurface layer on said first substrate and thereafter executing the stepof providing said devices in said surface layer
 36. The method asrecited in claim 35 further comprising the step of: thinning said firstsubstrate, and isolating through form and functioning the individualdevices of said array.
 37. The method as recited in claim 36 whereinsaid isolating step includes a mesa etch for isolating the individualdevices.
 38. The method as recited in claim 37 wherein said markers inor on said second substrate are provided with a substantiallycorresponding image thereof as used for defining the array of devices.39. A method of fabricating an optoelectrical device comprising thesteps of: growing a surface layer on a first substrate; providing anarray of devices for emitting and/or detecting electromagnetic radiationin said surface layer; attaching said first substrate to a secondsubstrate, said surface layer being on said second substrate; providingmarkers in or on said second substrate thereby ensuring that saidmarkers are aligned with the devices of said array; providing electricalconnections to said array of devices, preferably thereby ensuring thatessentially each of said devices are addressed individually
 40. Themethod as recited in claim 38 wherein said second substrate istransparent for said radiation
 41. The method as recited in claim 38further comprising the step of: thinning said first substrate, andisolating through form and functioning the individual devices of saidarray.
 42. The method as recited in claim 38 wherein said markers in oron said second substrate are provided with a substantially correspondingimage thereof as used for defining the array of devices.
 43. A method offabricating an optoelectrical apparatus comprising the steps of: growinga surface layer on a first substrate; attaching said first substrate toa second substrate, said surface layer being on said second substrate,providing an array or devices for emitting and/or detectingelectromagnetic radiation in said surface layer providing markers in oron said second substrate thereby ensuring that said markers are alignedwith the devices of said array; providing electrical connections to saidarray of devices, preferably thereby ensuring that essentially each ofsaid devices are addressed individually.